Tangential volumetric modulated arc therapy technique for left-sided breast cancer radiotherapy

Abstract

BackgroundThe aim of the present study was to introduce a new restricted tangential volumetric modulated arc therapy (tVMAT) technique for whole breast irradiation and compare its dosimetric properties to other currently used breast cancer radiotherapy techniques.MethodTen consecutive women with left-sided breast cancer were enrolled in this retrospective study. Four treatment plans were generated for each patient: 1) standard tangential field-in-field (FinF), 2) tangential intensity modulated radiotherapy (tIMRT), 3) tangential VMAT (tVMAT) with two dual arcs of 50-60° and 4) continuous VMAT (cVMAT) with a dual arc of 240°. The plans were created with Monaco® (tIMRT, tVMAT and cVMAT) and Oncentra® (FinF) treatment planning systems.ResultsWith both VMAT techniques significantly higher cardiac avoidance, dose coverage and dose homogenity were achieved when compared with FinF or tIMRT techniques (p < 0.01). VMAT techniques also decreased the high dose areas (above 20 Gy) of ipsilateral lung. There were no significant differences in the mean dose of contralateral breast between the tVMAT, tIMRT and FinF techniques. The dose coverage (V47.5 Gy) was greatest with cVMAT. However, with cVMAT the increase of contralateral breast dose was significant.ConclusionsThe present results support the hypothesis that the introduced tVMAT technique is feasible for treatment of left-sided breast cancer. With tVMAT dose to heart and ipsilateral lung can be reduced and the dose homogeneity can be improved without increasing the dose to contralateral breast or lung.

Dosimetric effects of anatomical deformations and positioning errors in VMAT breast radiotherapy

“…However, there is an increasing trend toward intensity‐modulated radiation therapy (IMRT) techniques and VMAT 3, 4, 5, 6, 7, 8, 9. In FinF and IMRT, there is a possibility to extend the field to the air outside the body to account for eventual changes of shape or swell of the breast tissue, but in Varian's Eclipse VMAT planning system the possibilities are limited to the use of an optimization bolus.…”

“…The VMAT has been shown to be a feasible treatment option for adjuvant RT of the breast 3, 4, 5, 6, 7, 8, 9. It has been shown to reduce the dose to the ipsilateral lung for both left‐ and right‐sided treatments, and to the heart for left‐sided targets 5, 6.…”

“…It has been shown to reduce the dose to the ipsilateral lung for both left‐ and right‐sided treatments, and to the heart for left‐sided targets 5, 6. However, in VMAT the allowance for tissue deformations is limited.…”

“…However, in VMAT the allowance for tissue deformations is limited. In the Monaco treatment planning system (Elekta AB, Stockholm, Sweden), the skin flash tool is implemented inside the VMAT plan optimizer 5. In tomotherapy (TomoTherapy Hi‐Art system, Madison, USA), the optimization of the dose to the skin is possible, but to allow for swelling, further extension of the field fluences requires additional bolus structures 10.…”

Comparison of semiautomated tangential VMAT with 3DCRT for breast or chest wall and regional nodes

“…This low‐dose bath to healthy organs has been associated with increased risk of secondary malignancies11, 12 and adverse cardiac events 13. A VMAT technique has been proposed that reduces this issue by using tangential VMAT partial arcs for treatment of the breast only 4, 15. This has been shown to reduce the volume of the patient receiving a low dose while maintaining good target coverage.…”